Originally Posted by SharpyWarpy
I've searched these forums and found nothing concrete on how to update TomTom One GPS.
A TomTom One is a simpler proposition than one of the later devices than one of the later devices that uses My TomTom (ie, it uses TomTom Home and not my TomTom).
...don't want to risk bricking my brother's TomTom!
That does make things more difficult. The TomTom software itself (no Wine, no unconventional things, no messing about) does sometimes brick the GPS units. I think that's because it does not always check that there is enough memory for the things that it is about to install, and having overrun the amount of memory, some things won't work. Maybe those are critical things, maybe they aren't.
Having said that the TomTom One is simpler, the advantage of that is that you plug it into a computer and it mounts like a USB drive. (And, when it does, if you explore your way around the filesystem on the TomTom, it should look quite familiar to you.)
The first thing that you should do is to back it up. Given a decent back up, you should have a decent shot at recovery if something does go wrong (...and, given that is a possibility that can't be completely ruled out...). Now, I don't know what you'd use under a different system, but with Konqueror and K3B you will have everything you need to write a backup DVD. If you are a Gnome user, you'd probably be trying something like Brasero, for example.
If, for example, you want to add colo(u)r schemes and POIs, you can do that just by copying them across from Linux to the appropriate place in the file hierarchy on the TomTom. For map updates, you could probably do the same trick of just copying the new map over the old one, but I haven't tried this so I don't know (that probably should have been in upper case and red, just to be sure that it doesn't get ignored).
You can, by the way, create colo(u)r schemes with a plain text editor (eg, kate, vi, etc, etc), but you probably shouldn't. There is a (windows) program called Color Scheme editor that does it, makes it easier to see the results immediately (and, therefore, you can work much more quickly) and it mostly works under Wine.
If I was doing this, my first thing to do would be to back up, however you choose to do it, then fire up Windows and use TomTom Home for the maps (keeping fingers firmly crossed) and then do any further fiddling about under Linux, but you could do everything under Windows, if that was more convenient. Updating the maps under Linux is a risk, but then updating the maps the 'correct' way is also a risk, although probably a smaller one and a closer to quantifiable one.